The present invention generally relates to a chasses housing for power electronics and, more specifically, to an integral cold plate/chassis (ICPC) housing for force-cooled power electronics.
The power electronics for aerospace applications plays a significant role in the modern aircraft and spacecraft industry. This is particularly true in the area of more electric architecture (MEA) for aircraft and military ground vehicles.
The commercial aircraft business is moving toward non-bleed air environmental control systems (ECS), variable-frequency (VF) power distribution systems and electrical actuation. Typical examples include the latest designs, such as the Boeing 7E7 and the Airbus jumbo A380. The next-generation Boeing airplane (replacement of 737), and the Airbus airplane (replacement of A320), will most likely use MEA. Some military aircraft already utilize MEA, including primary and secondary flight control. Military ground vehicles have migrated toward hybrid electric technology where the main propulsion is electric drives. Therefore substantial demand for power utilization has arisen.
Resulting from these tendencies is a significant increase in power conversion needs. Non-bleed ECS's need additional electric drives for vapor cycle system (VCS) compressors, condenser fans and liquid pumps. A large number of electric drives for fans are required. In constant-frequency applications, these fans have used predominantly direct drive (no power electronics) to an induction machine. In the new environment, a double power electronics conversion AC to DC and DC to AC is required. Auxiliary power unit (APU) and main engine electric start imposes a need for high-power, multiple-use controllers. Military aircraft require high-voltage (270-Vdc) power conversions multiple times. Flight Control Systems (FCS) have moved toward 610-VDC power distribution system where high-power bidirectional propulsion is being used for driving and dynamic braking. The power generation is achieved by a main engine shaft driving a large electric machine(s). Again, bidirectional conversion is required for power conditioning and self-starting.
In this environment, it is obvious that there is a need for power converters and motor controllers for aircraft and ground military businesses for increased power levels conversion capabilities to handle increased loads; reduced controller weights to be able to accommodate large content increase per platform; reduced volume to accommodate electronics housings in limited compartments space; increased reliability for achieving reasonable mission success; and reduced cost for affordability.
The power range for power conversion and motor control units varies from hundreds of watts to hundreds of kilowatts. The efficiency of these converters varies from 80 to 97%. Therefore, heat rejection from 3 to 20% of the total converted power is required. For power conversion levels above several kilowatts, forced cooling is typically needed to achieve acceptable power density levels. The forced cooling is either air or liquid. The proper utilization of the coolant flow is achieved by using special devices called cold plates both for liquids and for air.
Cold plates with double-sided population of components and brazed fins are very popular in the industry because they provide greater utilization of surfaces. The brazing process forms a sandwich-like construction in which fins are permanently attached to two inner planes of the two flat metal side pieces. At the same time, containment for the air or liquid flow is achieved. The outer surfaces of the side pieces are available for installing power-dissipating components. In some cases, the cold plate can be used as a structural carrier for heavy components.
The remaining parts of the housing are typically made from sheet metal pieces preformed, bended, punched, drilled and then bolted to the heat exchanger, or glued, or glued and bolted. These parts can be machined from solid aluminum material, instead of using metal sheet, and assembled by using similar methods.
This method, and variations of it, contains a large number of machining and manual operations. Also material utilization is not optimized. The result is a heavy and expensive housing.
As can be seen, there is a need for a new construction and fabrication process for power electronics housings with improved performance and reduced cost that can improve power density, reliability and water splash resistance.